Imaging endoluminal instruments can be used to record two-dimensional images of the interior of a hollow channel, in particular of a vessel or of a hollow organ. Use is made here of imaging methods such as intravascular ultrasound (IVUS), optical coherence tomography (OCT) or fluorescent imaging. The image is recorded during the continuous or gradual controlled movement of the instrument in the hollow channel. Thus for example imaging intravascular catheters can provide two-dimensional sectional images from the interior of vessels, e.g. from the vascular system of the heart. FIG. 1 shows by way of example a section through the vascular system 3 of the heart, it being possible to identify the imaging catheter 1 inserted into one of the vessels 2. This catheter 1 is moved forward or backward with a movement control device 4 either mechanically or manually in the vessel 2. The trajectory direction of the catheter 1 is indicated by the arrow. During the continuous, controlled movement of the catheter 1 in the vessel 2 two-dimensional sectional images of the vessel are recorded at regular intervals. FIG. 1 shows, on the right, the 2D sectional images 5 which are obtained during the movement of the catheter 1 at various positions in the vessel 2 and which in each case represent a section transverse to the longitudinal axis of the vessel 2. The arrow running along the 2D sectional images 5 represents the trajectory direction of the catheter 1 while the image is being recorded. In the 2D sectional images the vascular wall 7 as well as the central axis 10 of the vessel within the vessel lumen 6 can be seen, on which axis the catheter 1 is guided. Since the longitudinal displacement of the catheter 1 at the time of each recording of a 2D sectional image 5 and thus also the relative displacement positions for each 2D sectional image are known as a result of the controlled catheter movement, the image data for these images can be compiled to form a three-dimensional image data record by taking into account the relative displacement positions.
Furthermore DE 199 19 907 A1 discloses a method for catheter navigation in three-dimensional vascular tree exposures, in which the spatial position of the catheter is detected and blended into a 3D view of a preoperatively recorded vascular tree. For this, use is made of a catheter with an integrated position sensor, via which the respective current spatial position of the catheter tip is detected. This position sensor is registered with the 3D image data before the intervention takes place, using special markers which are visible in the 3D image and which are approached with the catheter. This type of registration is required for all applications in which the recorded 2D image data is to be combined with 3D image data.